QoS Tunnel Marking for GRE Tunnels

The QoS Tunnel Marking for GRE Tunnels feature introduces the capability to define and control the quality of service (QoS) for both incoming and outgoing customer traffic on the provider edge (PE) router in a service provider network.

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Prerequisites for QoS Tunnel Marking for GRE Tunnels

  • You must determine the topology and interfaces that need to be configured to mark incoming and outgoing traffic.

Restrictions for QoS Tunnel Marking for GRE Tunnels

  • GRE tunnel marking is not supported on the following paths:
    • IPsec tunnels
    • Multiprotocol Label Switching over generic routing encapsulation (MPLSoGRE)
    • Layer 2 Tunneling Protocol (L2TP)

Information About QoS Tunnel Marking for GRE Tunnels

GRE Definition

Generic routing encapsulation (GRE) is a tunneling protocol developed by Cisco that can encapsulate a wide variety of protocol packet types inside IP tunnels, creating a virtual point-to-point link to Cisco routers at remote points over an IP internetwork.

GRE Tunnel Marking Overview

The QoS Tunnel Marking for GRE Tunnels feature allows you to define and control QoS for incoming and outgoing customer traffic on the PE router in a service provider (SP) network. This feature lets you set (mark) either the IP precedence value or the differentiated services code point (DSCP) value in the header of an GRE tunneled packet. GRE tunnel marking can be implemented by a QoS marking command, such as set ip {dscp | precedence} [tunnel], and it can also be implemented in QoS traffic policing. This feature reduces administrative overhead previously required to control customer bandwidth by allowing you to mark the GRE tunnel header on the tunnel interface on the PE routers.

Note

The set ip {dscp | precedence} [tunnel] command is equivalent to the set {dscp | precedence} [tunnel] command.

The figure below shows traffic being received from the CE1 router through the incoming interface on the PE1 router on which tunnel marking occurs. The traffic is encapsulated (tunneled), and the tunnel header is marked on the PE1 router. The marked packets travel (tunnel) through the core and are decapsulated automatically on the exit interface of the PE2 router. This feature is designed to simplify classifying customer edge (CE) traffic and is configured only in the service provider network. This process is transparent to the customer sites. The CE1 and CE2 routers exist as a single network.

Figure 1. Tunnel Marking

GRE Tunnel Marking and the MQC

Before you can configure tunnel marking for GRE tunnels, you must first configure a class map and a policy map and then attach that policy map to the appropriate interface. These three tasks can be accomplished by using the MQC.

For information on using the MQC, see the “Applying QoS Features Using the MQC” module.

GRE Tunnel Marking and DSCP or IP Precedence Values

GRE tunnel marking is configured with the set ip precedence tunnel or set ip dscp tunnel command on PE routers that carry incoming traffic from customer sites. GRE tunnel marking allows you to mark the header of a GRE tunnel by setting a DSCP value from 0 to 63 or an IP precedence value from 0 to 7 to control GRE tunnel traffic bandwidth and priority.

GRE traffic can also be marked under traffic policing with the set-dscp-tunnel-transmit and the set-prec-tunnel-transmit actions (or keywords) of the police command. The tunnel marking value is from 0 to 63 for the set-dscp-tunnel-transmit actions and from 0 to 7 for the set-prec-tunnel-transmit command. Under traffic policing, tunnel marking can be applied with conform, exceed, and violate action statements, allowing you to automatically apply a different value for traffic that does not conform to the expected traffic rate.

After the tunnel header is marked, GRE traffic is carried through the tunnel and across the service provider network. This traffic is decapsulated on the interface of the PE router that carries the outgoing traffic to the other customer site. The configuration of GRE tunnel marking is transparent to customer sites. All internal configuration is preserved.

There is a different between the set ip precedence and set ip dscp commands and the set ip precedence tunnel and set ip dscp tunnel commands:

  • The set ip precedence and set ip dscp commands are used to set the IP precedence value or DSCP value in the header of an IP packet.

  • The set ip precedence tunnel and set ip dscp tunnel commands are used to set (mark) the IP precedence value or DSCP value in the tunnel header that encapsulates the GRE traffic.

  • The set ip precedence tunnel and set ip dscp tunnel commands have no effect on egress traffic that is not encapsulated in a GRE tunnel.

Benefits of GRE Tunnel Marking

GRE tunnel marking provides a simple mechanism to control the bandwidth of customer GRE traffic. The QoS Tunnel Marking for GRE Tunnels feature is configured entirely within the service provider network and on interfaces that carry incoming and outgoing traffic on the PE routers.

GRE Tunnel Marking and Traffic Policing

Traffic policing allows you to control the maximum rate of traffic sent or received on an interface and to partition a network into multiple priority levels or class of service (CoS). If you use traffic policing in your network, you can also implement the GRE tunnel marking feature with the set-dscp-tunnel-transmit or set-prec-tunnel-transmit action (or keyword) of the police command in policy-map class configuration mode. Under traffic policing, tunnel marking can be applied with conform, exceed, and violate action statements, allowing you to apply a different value automatically for traffic that does not conform to the expected traffic rate.

GRE Tunnel Marking Values

The range of the tunnel marking values for the set ip dscp tunnel and set-dscp-tunnel-transmit commands is from 0 to 63, and the range of values for the set ip precedence tunnel and set-prec-tunnel-transmit commands is from 0 to 7.

How to Configure Tunnel Marking for GRE Tunnels

Configuring a Class Map

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    class-map [match-all | match-any] class-map-name

    4.    match ip precedence precedence-value

    5.    exit

    6.    class-map [match-all | match-any] class-map-name

    7.    match ip dscp dscp-value

    8.    end


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example:
    Router> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.

     
    Step 2 configure terminal


    Example:
    Router# configure terminal
     

    Enters global configuration mode.

     
    Step 3 class-map [match-all | match-any] class-map-name


    Example:
    Router(config)# class-map match-any MATCH_PREC
     

    Specifies the name of the class map to be created and enters QoS class map configuration mode.

    • The class map defines the criteria to use to differentiate the traffic. For example, you can use the class map to differentiate voice traffic from data traffic, based on a series of match criteria defined using the match command.

    Note   

    If the match-all or match-any keyword is not specified, traffic must match all the match criteria to be classified as part of the traffic class.

     
    Step 4 match ip precedence precedence-value


    Example:
    Router(config-cmap)# match ip precedence 0
     

    Enables packet matching on the basis of the IP precedence values you specify.

    Note   

    You can enter up to four matching criteria, as number abbreviation (0 to 7) or criteria names (critical, flash, and so on), in a single match statement.

     
    Step 5 exit


    Example:
    Router(config-cmap)# exit
     

    Returns to global configuration mode.

     
    Step 6 class-map [match-all | match-any] class-map-name


    Example:
    Router(config)# class-map match-any MATCH_DSCP
     

    Specifies the name of the class map to be created and enters QoS class map configuration mode.

     
    Step 7 match ip dscp dscp-value


    Example:
    Router(config-cmap)# match ip dscp 0
     

    Enables packet matching on the basis of the DSCP values you specify.

    • This command is used by the class map to identify a specific DSCP value marking on a packet.

    • The treatment of these marked packets is defined by the user through the setting of QoS policies in policy-map class configuration mode.

     
    Step 8 end


    Example:
    Router(config-cmap)# end
     

    (Optional) Returns to privileged EXEC mode.

     

    Creating a Policy Map

    Perform this task to create a tunnel marking policy marp and apply the map to a specific interface.

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    policy-map policy-map-name

      4.    class {class-name | class-default}

      5.    set ip precedence tunnel precedence-value

      6.    exit

      7.    class {class-name | class-default}

      8.    set ip dscp tunnel dscp-value

      9.    end


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 enable


      Example:
      Router> enable
       

      Enables privileged EXEC mode.

      • Enter your password if prompted.

       
      Step 2 configure terminal


      Example:
      Router# configure terminal
       

      Enters global configuration mode.

       
      Step 3 policy-map policy-map-name


      Example:
      Router(config)# policy-map TUNNEL_MARKING
       

      Creates or modifies a policy map that can be attached to one or more interfaces to specify a service policy, and enters QoS policy-map configuration mode.

       
      Step 4 class {class-name | class-default}


      Example:
      Router(config-pmap)# class MATCH_PREC
       

      Specifies the name of the class whose policy you want to create or change or specifies the default class (commonly known as the class-default class) before you configure its policy.

      • Enters policy-map class configuration mode.

       
      Step 5 set ip precedence tunnel precedence-value


      Example:
      Router(config-pmap-c)# set ip precedence tunnel 3
       

      Sets the IP precedence value in the tunnel header of a GRE-tunneled packet on the ingress interface. The tunnel marking value is a number from 0 to 7 when IP precedence is configured.

       
      Step 6 exit


      Example:
      Router(config-pmap-c)# exit
       

      Returns to QoS policy-map configuration mode.

       
      Step 7 class {class-name | class-default}


      Example:
      Router(config-pmap)# class MATCH_DSCP
       

      Specifies the name of the class whose policy you want to create or change or specifies the default class (commonly known as the class-default class) before you configure its policy.

      • Enters policy-map class configuration mode.

       
      Step 8 set ip dscp tunnel dscp-value


      Example:
      Router(config-pmap-c)# set ip dscp tunnel 3
       

      Sets the differentiated services code point (DSCP) value in the tunnel header of a GRE-tunneled packet on the ingress interface. The tunnel marking value is a number from 0 to 63 when DSCP is configured.

       
      Step 9 end


      Example:
      Router(config-pmap-c)# end
       

      (Optional) Returns to privileged EXEC mode.

       

      Attaching the Policy Map to an Interface or a VC

      Policy maps can be attached to main interfaces, subinterfaces, or ATM permanent virtual circuits (PVCs). Policy maps are attached to interfaces by using the service-policy command and specifying either the input or output keyword to indicate the direction of the interface.

      Note

      Tunnel marking policy can be applied on Ingress or Egress direction. A tunnel marking policy can be applied as an ingress policy on the ingress physical interface of a Service Provider Edge (SPE) router or as an egress policy on a tunnel interface.

      SUMMARY STEPS

        1.    enable

        2.    configure terminal

        3.    interface type number

        4.    service-policy {input | output} policy-map-name

        5.    end


      DETAILED STEPS
         Command or ActionPurpose
        Step 1 enable


        Example:
        Router> enable
         

        Enables privileged EXEC mode.

        • Enter your password if prompted.

         
        Step 2 configure terminal


        Example:
        Router# configure terminal
         

        Enters global configuration mode.

         
        Step 3 interface type number


        Example:
        Router(config)# interface GigabitEthernet 0/0/1
         

        Configures an interface type and enters interface configuration mode.

         
        Step 4 service-policy {input | output} policy-map-name

        Example:
        Router(config-if)# service-policy input TUNNEL_MARKING
         

        Specifies the name of the policy map to be attached to the input or output direction of the interface.

        • Policy maps can be configured on ingress or egress routers. They can also be attached in the input or output direction of an interface. The direction (input or output) and the router (ingress or egress) to which the policy map should be attached vary according your network configuration.

         
        Step 5 end


        Example:
        Router(config-if)# end
         

        (Optional) Returns to privileged EXEC mode.

         

        Verifying the Configuration of Tunnel Marking for GRE Tunnels

        Use the show commands in this procedure to view the GRE tunnel marking configuration settings. The show commands are optional and can be entered in any order.

        SUMMARY STEPS

          1.    enable

          2.    show policy-map interface interface-name

          3.    show policy-map policy-map

          4.    exit


        DETAILED STEPS
           Command or ActionPurpose
          Step 1 enable


          Example:
          Router> enable
           

          Enables privileged EXEC mode.

          • Enter your password if prompted.

           
          Step 2 show policy-map interface interface-name


          Example:
          Router# show policy-map interface GigabitEthernet0/0/1
           

          (Optional) Displays the packet statistics of all classes that are configured for all service policies either on the specified interface or subinterface.

           
          Step 3 show policy-map policy-map


          Example:
          Router# show policy-map TUNNEL_MARKING
           

          (Optional) Displays the configuration of all classes for a specified service policy map or all classes for all existing policy maps.

           
          Step 4 exit


          Example:
          Router# exit
           

          (Optional) Returns to user EXEC mode.

           

          Troubleshooting Tips

          If you find that the configuration is not functioning as expected, perform these operations to troubleshoot the configuration:

          • Use the show running-config command and analyze the output of the command.

          • If the policy map does not appear in the output of the show running-config command, enable the logging console command.

          • Attach the policy map to the interface again.

          Configuration Examples for QoS Tunnel Marking for GRE Tunnels

          Example: Configuring Tunnel Marking for GRE Tunnels

          The following is an example of a GRE tunnel marking configuration. In this example, a class map called “MATCH_PREC” has been configured to match traffic based on the DSCP value. 

          Router> enable
Router# configure terminal
Router(config)# class-map MATCH_DSCP 
Router(config-cmap)# match ip dscp 0
Router(config-cmap)# end

          In the following part of the example configuration, a policy map called “TUNNEL_MARKING” has been created and the set ip dscp tunnel command has been configured in the policy map. You could use the set ip precedence tunnel command instead of the set ip dscp tunnel command if you do not use DSCP in your network. 

          Router(config)# policy-map TUNNEL_MARKING
Router(config-pmap)# class MATCH_DSCP
Router(config-pmap-c)# set ip dscp tunnel 3
Router(config-pmap-c)# end

          Note

          The following part of the example configuration is not required to configure this feature if you use the set ip dscp tunnel or set ip precedence tunnel commands to enable GRE tunnel marking. This example shows how GRE tunnel marking can be enabled under traffic policing.

          In the following part of the example configuration, the policy map called “TUNNEL_MARKING” has been created and traffic policing has also been configured by using the police command and specifying the appropriate policing actions. The set-dscp-tunnel-transmit command can be used instead of the set-prec-tunnel-transmit command if you use DSCP in your network. 

          Router(config)# policy-map TUNNEL_MARKING
Router(config-pmap)# class class-default
Router(config-pmap-c)# police 8000 conform-action set-prec-tunnel-transmit 4 exceed-action set-prec-tunnel-transmit 0
Router(config-pmap-c)# end

          In the following part of the example configuration, the policy map is attached to GigabitEthernet interface 0/0/1 in the inbound (input) direction by specifying the input keyword of the service-policy command: 

          Router(config)# interface GigabitEthernet 0/0/1
Router(config-if)# service-policy input TUNNEL_MARKING 
Router(config-if)# end

          In the final part of the example configuration, the policy map is attached to tunnel interface 0 in the outbound (output) direction using the output keyword of the service-policy command: 

          Router(config)# interface Tunnel 0
Router(config-if)# service-policy output TUNNEL_MARKING 
Router(config-if)# end

          Example: Verifying the Tunnel Marking for GRE Tunnels Configuration

          This section contains sample output from the show policy-map interface and the show policy-map commands. The output from these commands can be used to verify and monitor the feature configuration in your network.

          The following is sample output from the show policy-map interface command. In this sample output:

          • The character string “ip dscp tunnel 3” indicates that GRE tunnel marking has been configured to set the DSCP value in the header of a GRE-tunneled packet.

          • The character string “ip precedence tunnel 3” indicates that GRE tunnel marking has been configured to set the precedence value in the header of a GRE-tunneled packet. 

           show policy-map interface GigabitEthernet0/0/1 
 Service-policy input: TUNNEL_MARKING

    Class-map: MATCH_PREC (match-any)
      22 packets, 7722 bytes
      5 minute offered rate 0000 bps, drop rate 0000 bps
      Match: ip precedence 0
      QoS Set
        ip precedence tunnel 3
          Marker statistics: Disabled

    Class-map: MATCH_DSCP (match-any)
      0 packets, 0 bytes
      5 minute offered rate 0000 bps, drop rate 0000 bps
      Match: ip dscp default (0)
      QoS Set
        ip dscp tunnel 3
          Marker statistics: Disabled

    Class-map: class-default (match-any)
      107 packets, 8658 bytes
      5 minute offered rate 0000 bps, drop rate 0000 bps
      Match: any

          The following is sample output from the show policy-map command. In this sample output, the character string “ip precedence tunnel 3” indicates that the GRE tunnel marking feature has been configured to set the IP precedence value in the header of an GRE-tunneled packet. 

           show policy-map

Policy Map TUNNEL_MARKING
    Class MATCH_PREC
      set ip precedence tunnel 3
    Class MATCH_DSCP
      set ip dscp tunnel 3

          Additional References

          Related Documents

          Related Topic

          Document Title

          Cisco IOS commands

          Cisco IOS Master Commands List, All Releases

          QoS commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples

          Cisco IOS Quality of Service Solutions Command Reference

          MQC

          “Applying QoS Features Using the MQC” module

          Tunnel marking for Layer 2 Tunnel Protocol Version 3 (L2TPv3) tunnels

          “QoS: Tunnel Marking for L2TPv3 Tunnels” module

          DSCP

          “Overview of DiffServ for Quality of Service” module

          Standards

          Standard

          Title

          No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

          --

          MIBs

          MIB

          MIBs Link

          No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.

          To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

          http:/​/​www.cisco.com/​go/​mibs

          RFCs

          RFC

          Title

          No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.

          --

          Technical Assistance

          Description

          Link

          The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

          http:/​/​www.cisco.com/​cisco/​web/​support/​index.html

          Feature Information for QoS Tunnel Marking for GRE Tunnels

          The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

          Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.
          Table 1 Feature Information for QoS Tunnel Marking for GRE Tunnels

          Feature Name

          Releases

          Feature Information

          QoS Tunnel Marking for GRE Tunnels

          Cisco IOS XE Release 3.5S

          The QoS Tunnel Marking for GRE Tunnels feature introduces the capability to define and control the QoS for incoming customer traffic on the PE router in a service provider network.

          The following commands were introduced or modified: match atm-clp, match cos, match fr-de, police, police (two rates), set ip dscp tunnel, set ip precedence tunnel, show policy-map, show policy-map interface.